To prepare the mixes: Combine the cake mix ingredients; set aside. Combine the first four Streusel ingredients; add pecans. Store both mixes in separate airtight containers in a cool dry place for up to 6 months. Yield: 3 batches (6 cups of cake mix, 2 1/4 cups of streusel).
To prepare coffee cake: In a mixing bowl, combine 2 cups of cake mix, egg, milk and oil; mix well. Pour into a greased 9-in. square baking pan.
Combine 3/4 cup streusel mix and butter; sprinkle over batter.
Bake at 375°F for 25-30 minutes or until a toothpick inserted near the center comes out clean. Serve warm. Yield: 9 servings per batch.